The present invention relates to packaging for mechanical parts. In particular, it relates to a packaging method for protecting mechanical parts during handling and dispensing to prevent contamination and avoid component damage.
In many industries, it is important to package and handle individual parts to avoid contamination and/or damage. The computer industry is an example. The present invention is described in the context of a computer hard disk but has applications beyond that component and industry.
Hard disk files are computer components which store information. A hard disk file typically has a magnetic recording disk and a magnetic read/write transducer for writing information onto the disk, and reading information from the disk. The transducer is mounted onto a magnetic recording head, which is supported by a spring attached to an actuator arm.
The spring, or flexure provides a force normal to the disk surface which allows the head to remain positioned very close to the disk surface as the disk spins. When the disk is spinning, an air cushion forms between the disk surface and the adjacent head surface, forcing the head away from the disk, in a direction normal to the disk surface. The spring, or flexure provides a force in a direction normal to the disk surface, which compensates for lifting motion of the magnetic recording head, and causes the head to remain close to the disk surface. When the disk comes to rest, the spring presses the head against the disk surface.
During disk file operation, the disk spins and a servo motor positions the magnetic read/write transducer above a track on the disk. As the servo motor moves the head from track to track on the disk surface, the acceleration of the actuator arm causes vibration in the actuator arm spring, which in turn causes the magnetic read/write transducer to vibrate. Also, movement of the head from position to position within the same track causes the actuator spring to oscillate. It is necessary to dampen the vibration in the spring of the actuator arm to maximize the speed in which the hard disk file operates. This dampening may be accomplished by a damper positioned on the spring.
Although it is known in the industry that placing a damper on the actuator arm spring is desirable, it has not been possible prior to the present invention, to handle the dampers without causing some contamination and/or damage. Contaminated and/or damaged dampers often cause the entire hard disk file component to fail quality control tests. The quality control failure of a hard disk file actuator arm, for example, requires that the actuator arm be returned to a clean room atmosphere and thoroughly cleaned before the defective damper is removed and replaced. Recleaning and repairing these components has proven to be both time consuming and expensive.
Presently, dampers are punch pressed from a strip of base stock material, which in a preferred embodiment is a multilayer laminate containing at least one layer of stainless steel. The total laminate thickness is typically about 0.003 inch thick. The stock material 10 is shown in FIG. 1 and has a lower surface which is coated with an adhesive (not shown). A release backing (not shown) is provided in the form of a release tape to protect the adhesive coating, and to prevent the dampers from adhering to the surfaces prior to their desired placement. The dampers 12 are punched from the stock material 10 with a punch press and are immediately returned to their original positions in the cut-out portions of the stock material. When the dampers are cut, the adhesive layer and release backing are also cut. As the dampers are returned to the cut-out areas of the sheet, the edges of the adhesive coating on the dampers bond to the outer edges of the cut-out areas, holding the dampers in place, forming a sheet of dampers as shown in FIG. 1. The dampers may be handled/shipped as a sheet prior to their use.
In order to use the dampers, it is necessary to first separate each damper from the sheet of dampers 10. Presently, this tedious task is accomplished by using very small tools such as tweezers, a pin vice, or a small knife for example. A typical damper 12 is of a substantially wedged shape which is less than one inch in length, and less than one quarter of an inch in width at the widest end. Individually removing each damper has proven to be very difficult and time consuming, and often results in mechanical damage such as dimpling, bending, and nicking. Physically handling the parts also creates more opportunity for exposure to contaminants.
Once each damper/backing has been separated from the sheet, the release backing must next be removed. A common release backing is available in the form of a release tape, and is typically constructed of paper which is coated with a wax or silicone. Although the bond between the adhesive and the wax coated paper is relatively weak, manufacturers who use the dampers have still found it difficult to remove the paper backing from the damper itself, due to the small size of the part. Removing the paper backing often requires the use of tools such as tweezers. This removal procedure often results in bending, and other mechanical damage to the dampers such as nicks, as well as contamination. The above-mentioned procedures are also time consuming and expensive.
Manufacturers of computer components have discovered that the use and handling of actuator arm spring dampers described above results in significant contamination and/or mechanical damage. If the damage or contamination goes undetected, reduced hard disk file performance or possible catastrophic disk drive failure is likely to be a result. If the damage or contamination is detected, additional disassembly, cleaning, and assembly steps are required to produce an acceptable product.
It is known in the art to deliver mechanical parts on a continuous, adhesive coated tape. For example, Okui U.S. Pat. No. 4,702,788 discloses a carrier tape structure having a first film layer with a series of aligned holes near the edge of the tape for receiving the teeth of a sprocket, and another series of aligned apertures near the center of the tape for receiving mechanical parts. Beneath the first film layer is attached a second film layer having an adhesive coating on both sides. The second film layer is wide enough to completely cover the apertures for receiving parts, but is narrow enough to avoid covering the sprocket holes. On the opposite side of the second film layer is a protective peel-off layer. Parts are positioned on the exposed adhesive surfaces on the first film layer. The second layer is severed along the boundary of each aperture so that when a part is removed, the portion of the second film layer contacting a surface of the part is removed with the part.